1. Field of the Invention
The present invention relates to a mowing machine suitable for cutting the grass on flat fields, ridges between rice fields, or grass fields including slanted surfaces.
2. Description of the Prior Art
Weeds on fields, particularly on ridges between rice fields, have to be cut several times a year because they are responsible for providing a nest of vermin. Heretofore, various mowing machines have been proposed to help farmers cut weeds.
Japanese utility model publication No. 61-40099 discloses a self-propelled mowing machine having a machine body supported by four front and rear wheels, an engine and a cutting blade which are supported on the machine body. When a slanted surface of a ridge is to be mowed, the disclosed mowing machine is tilted as a whole so as to adapt itself to the slanted surface. The disclosed mowing machine is characterized in that the lateral spacing between the wheels can be reduced if the slanted surface is relatively small.
FIG. 16 of the accompanying drawings shows an ideal ridge in cross section, and FIG. 17 of the accompanying drawings shows an actual ridge in cross section.
In FIG. 16, a ridge 90 has a cross-sectional shape of an isosceles trapezoid including an upper surface 101 and a pair of opposite slanted surfaces 102. A four-wheeled mowing machine 103 that is in an inclined position P on one of the slanted surfaces 102 is possible to cut the grass on that slanted surface 102 provided the user securely grips a handle 105. The four-wheeled mowing machine 103 that is in a position Q on the upper surface 101 is also possible to cut the grass on the upper surface 101 also provided the user securely grips the handle 105.
Actually, most ridges have round corners as indicated by 110 in FIG. 17. The ridge 110 has no sharp edges for preventing the wheels of the mowing machine 103 from laterally skidding downwardly. Even if the user of the mowing machine 103 strongly holds the handle 105 and attempts to keep the mowing machine 103 vertically on the upper surface of the ridge 110, the mowing machine 103 tends to slip laterally and fall as indicated by the arrow. Since an engine 106 is positioned above a cutting blade 104 (see FIG. 16), the center of gravity of the mowing machine 103 is so high that the mowing machine 103 is liable to fall in use. Therefore, the conventional four-wheeled mowing machine 103 places a large physical and mental burden on the user while it is in use.